<p>Plants and mycorrhizal fungi form a mutualism in which plants donate carbon to the fungus and, in return, receive benefits such as increased nutrient uptake and water. Mycorrhizal fungi colonize plant roots, forming nutrient exchange structures. The fungi also colonize the soil by growing long strands of hyphae that forage for nutrients and attach plants, forming a common mycorrhizal network (CMN). Plants attached to a well-supported CMN will receive greater benefits than those attached to a lesser CMN because the more carbon donations the fungal partner receives, the more it can grow and colonize the soil, accessing hard to reach soil nutrients. Kin selection theory predicts that relatives should donate more carbon to the fungal partner than non-relatives because benefits gained by neighbouring relatives through the CMN lead to inclusive fitness gains. Thus, social environment, i.e. relatedness of the group, could affect the mycorrhizal mutualism. Moreover, the presence of mycorrhizal fungi in the soil could affect plant responses to their social environment.</p> <p>For my PhD thesis I have investigated whether mycorrhizal fungi respond to plant social environment and whether the presence of mycorrhizal fungi affects plant responses to relatedness. I have addressed these topics in three greenhouse studies and two field studies, using herbaceous plants and trees. I have found strong evidence that siblings have an increased association with their mycorrhizal partner compared to strangers, resulting in greater benefits for siblings. Taken together, the results from this thesis demonstrate that the ability for plants to recognize kin has implications beyond intra-specific competitive interactions and that plant social environment has important effects on a widespread inter-specific mutualism. Additionally, the recently discovered phenomenon of plant kin recognition has been put into the context of mycorrhizae, and I have shown that mycorrhizal plants respond differently to their social environment than non-mycorrhizal plants.</p> / Doctor of Philosophy (PhD)

Kin recognition is the ability to identify a conspecific as a relative and can occur even when animals are complete strangers. By being able to recognise relatives, animals are able to give preferential treatment to those with which they share genes. Recognition may occur by either direct familiarisation (learning a phenotypic cue that reliably correlates to kinship), or by indirect familiarisation (learning kinship relationships through previous encounters). Rats (Rattus norvegicus) can recognise kin, however to what degree kin recognition is mediated by genetics (direct familiarisation) or social relationships (indirect familiarisation) are unknown; the influences of kinship and familiarity on the ability to learn from a conspecific is also unknown. Furthermore, the sex of an animal can also influence its ability to learn but this effect has received little attention in the literature, particularly when considering observational learning tasks. I assessed if relatedness and/or familiarity influenced a rat's ability to learn through observation, and if gender relationships influence the learning process. Eighty rats ( observers ) were given the opportunity to observe a demonstrator rat press a joystick in a given direction to obtain a food reward. Observers watched a demonstrator that had one of the following relationships with them: related and familiar, related and unfamiliar, unrelated and familiar, or unrelated and unfamiliar. When observers were given the opportunity to manipulate the joystick, the number of sniffs of the joystick, the latency to first move the joystick and the total number of presses were recorded. Rats that were both familiar and related to the demonstrator consistently performed better than any other treatment group; furthermore, rats that were familiar with the demonstrator performed the task more efficiently than rats that were not familiar with the demonstrator. When the demonstrators and observers were related, the observers produced more presses and sniffs of the joystick while having a lower latency to the first push In addition, male observers learnt better than females regardless of the demonstrator sex, with males that were familiar to their demonstrator making nearly twice as many pushes than any other treatment group. The results from this study are discussed in relation to both the mechanisms of direct and indirect recognition and the potential adaptive value on kin discrimination in the learning process. The home range hypothesis may explain why gender differences in learning were found: male rats have larger home ranges than females. Male rat will regularly encounter more rats than females and would need to ascertain if unfamiliar individuals are relatives. Females remain closer to natal sites and as such are more likely to encounter kin and therefore may not need as well as developed kin recognition ability.

The core of sociality and one of the key forces behind the transition to multicellularity is cooperation. The study of social behavior in microorganisms has gained considerable attention in the last decade as researchers have discovered that many of the cooperative social interactions found in higher organisms can also be found in microbes. The dictyostelids are particularly amenable to the study of social evolution because of the potential for conflict and cooperation during multicellular formation. The formation of the multicellular fruiting body may lead to conflict because all nearby cells aggregate together, which may be distinct clones, each trying to increase its own fitness. I first explored how D. discoideum and D. purpureum interact and if either species looks to cheat the other when they interact. I found that both species prefer being clonal but cooperate with each other when it seems the benefits outweigh the costs. Cooperating amoebae are able to make larger fruiting bodies, which are advantageous for migration and dispersal, but both species suffer a cost in producing fewer spores per fruiting body. I next examined short-range social dispersal in the social amoebae, D. discoideum and D. purpureum. It appears that the evolutionary loss of stalked migration gives D. discoideum cells the advantage of delaying specialization and the ability to colonize more distant locations, but has significant costs due to migration distance, such as the fraction of cells that become fertile spores. In my final study, we examine the interaction of different clones of D. discoideum before and after migration. We show that chimerism and migration interact to produce fruiting bodies that have a proportionally higher spore allocation compared to clonal fruiting bodies after migration but were unable to determine whether the results that we see are an indication of clones defecting in a tragedy of the commons or more cooperation. With further study will be able to better explain the affects of cooperation on group dispersal and whether it can be used as a mechanism to reduce local competition.

Thesis (Ph.D.)--McMaster University, 2003. / Includes bibliographical references (p. 87-97) Also available via World Wide Web.

abstract: Arguments of human uniqueness emphasize our complex sociality, unusual cognitive capacities, and language skills, but the timing of the origin of these abilities and their evolutionary causes remain unsolved. Though not unique to primates, kin-biased sociality was key to the success of the primate order. In contrast to ancestral solitary mammals, the earliest primates are thought to have maintained dispersed (non-group living) social networks, communicating over distances via vocalizations and scent marks. If such ancestral primates recognized kin, those networks may have facilitated the evolution of kin-biased sociality in the primate order and created selection for increased cognitive and communicative abilities. I used the gray mouse lemur (Microcebus murinus) to model whether vocalizations could have facilitated matrilineal and patrilineal kin recognition in ancestral primates. Much like mouse lemurs today, ancestral primates are thought to have been small-bodied, nocturnal creatures that captured insects and foraged for fruit in the thin, terminal ends of tree branches. Thus, the mouse lemur is an excellent model species because its ecological niche is likely to be similar to that of ancestral primates 55-90 million years ago. I conducted playback experiments in Ankarafantsika National Park, Madagascar testing whether mouse lemur agonistic calls contain matrilineal kin signatures and whether the lemurs recognize matrilineal kin. In contrast to large-brained, socially complex monkeys with frequent coalitionary behavior, mouse lemurs did not react differently to the agonistic calls of matrilineal kin and nonkin, though moderate signatures were present in the calls. I tested for patrilineal signatures and patrilineal kin recognition via mating and alarm calls in a colony with known pedigree relationships. The results are the first to demonstrate that a nocturnal, solitary foraging mammal gives mating calls with patrilineal signatures and recognizes patrilineal kin. Interestingly, alarm calls did not have signatures and did not facilitate kin recognition, suggesting that selection for kin recognition is stronger in some call types than others. As this dissertation is the first investigation of vocal kin recognition in a dispersed-living, nocturnal strepsirrhine primate, it greatly advances our knowledge of the role of vocal communication in the evolution of primate social complexity. / Dissertation/Thesis / Ph.D. Anthropology 2014

La consanguinité est connue par les biologistes pour diminuer la valeur sélective des individus en diminuant par exemple leur survie ou leur fertilité. De ce fait, la sélection naturelle devrait favoriser l'apparition de comportements permettant l'évitement des accouplements entre apparentes pour limiter les conséquences néfastes dues à la dépression de consanguinité. Cette dépression de consanguinité est particulièrement visible chez les Hyménoptères avec un système de détermination du sexe appelé single-locus Complementary Sex Determination (sl-CSD), où elle amène à la production de males diploïdes non viables ou stériles. Mon travail de thèse a ainsi consiste à étudier le phénomène d'évitement d'accouplements entre apparentes dans des populations naturelles d'un hyménoptère parasitoïde avec sl-CSD, Venturia canescens, ainsi que des signaux utilisés par les femelles pour déterminer l'apparentement qu'elles ont avec les individus qu'elles rencontrent. Nous avons d'abord étudié le lien unissant type d'habitat (continental, iles ou laboratoire), diversité génétique et production de males diploïdes dans 11 populations de V. canescens. En effet, un cadre théorique nomme "Vortex d'extinction du aux males diploïdes" prédit une corrélation négative entre isolations des populations, diversité génétique et production de males diploïdes pouvant amener à l'extinction de populations d'Hyménoptères. Nous avons ainsi démontré une corrélation négative entre diversité génétique et production de males diploïdes dans les populations isolées de V. canescens. Ensuite, il a été montré précédemment que les femelles de cette espèce étaient capables de discriminer les males qui leur étaient apparentes et d'éviter les accouplements entre apparentes en laboratoire. Nous nous sommes ainsi intéressés à ce phénomène d'évitement d'accouplement entre apparentes dans des populations naturelles grâce au génotypage de 450 individus du terrain et leur descendants. Nous avons montré que les femelles toléraient les accouplements entre apparentes sur le terrain ainsi qu'en laboratoire en présence de plusieurs males, nous permettant de mettre en lumière l'importance des conditions environnementales sur le choix du partenaire sexuel. Nous nous sommes enfin concentrés sur le système de reconnaissance des apparentes au niveau mécanistique en étudiant les signaux chimiques utilisés par les femelles pour reconnaitre leurs apparentes dans deux contextes écologiques différents, le choix du partenaire sexuel et l'évitement du superparasitisme lors de la ponte. Nous avons ainsi montré des similitudes entre les compositions chimiques de ces deux signaux mais aussi qu'ils n'étaient pas interchangeables entre les deux contextes écologiques étudiés. Au final, les résultats obtenus apportent un nouvel éclairage sur les conditions nécessaires à l'apparition d'un évitement d'accouplements entre apparentes dans des populations naturelles ainsi que sur les signaux utilisés lors de la reconnaissance de parentèle chez un hyménoptère parasitoïde / Inbreeding is well known by biologists to lower the fitness of individuals by or example decreasing survival or fertility. Therefore, natural selection should favour behaviours preventing the reproduction of genetically-related individuals or mitigating harmful consequences, called inbreeding depression. Inbreeding depression is particularly visible in Hymenoptera with a sex-determination system called single-locus Complementary Sex Determination (sl-CSD), where it leads to the production of diploid males that are either unviable or sterile. My PhD work has thus been devoted to the study of sib-mating avoidance in natural populations of a parasitoid with sl-CSD, Venturia canescens, and to understand the cues used by females recognize their kin. We first studied the link between habitat type (continental, island or captive), genetic diversity and diploid male production in 11 V. canescens populations. Indeed, a theoretical framework called "Diploid male extinction vortex" predict a negative correlation between populations’ isolation, genetic diversity and diploid male production that could lead to the extinction of hymenopteran populations.We actually showed a negative correlation between genetic diversity and diploid male production in isolated populations. Previous studies have furthermore demonstrated kin discrimination and sib-mating avoidance by V. canescens females in the laboratory. We therefore studied the sibmating avoidance behaviour in natural populations of this species by genotyping more than 450 wild individuals and their offsprings. We demonstrated that females tolerated inbreeding in the wild as well as in the laboratory when several males were present. We highlighted the importance of environmental conditions on mate choice. At last, we were interested in the kin recognition system and researched the chemical cues used by females in two ecological contexts, mate choice and superparasitism avoidance. This allowed us to identify similarities in the composition of the two chemical signals and that they were not interchangeable between the two studied ecological contexts. In the end, the results we obtained shed new light on the necessary conditions for the apparition of sib-mating avoidance in natural populations, as well as on the cues used for kin recognition in a parasitoid

Conflicts over reproduction are common in animal societies and they are especially pronounced in groups of totipotent individuals. Workers in the drywood termite Cryptotermes secundus are totipotent. They can gain direct fitness via dispersal as winged sexual or inheritance of the natal nest as neotenic replacement reproductive. In this study we examined the actual conflict behaviour in C. secundus, possible mechanism of conflict-regulation, and factors influencing the conflict intensity. Cuticular hydrocarbons provided the information about nestmates which is required for mechanisms of conflict-resolution to work: they were (i) caste-specific, (ii) honest signal of fertility in neotenic queens, as they are reflecting the underlying JH titres mediated via caste-specific Neofem4 expression, and (iii) may also be informative enough to allow kin discrimination. Kin discrimination in C. secundus depended on social context and the individuals’ developmental potential. Sterile soldiers for example showed nepotistic grooming independent from the social context, but affected by wood resource, in contrast to workers that did not react to varying relatedness. Individuals showed distinct behavioural profiles before and during conflict, reflecting their reproductive potential: most prominent in the distinction were the dominance behaviour butting and proctodeal trophallaxis. The proposed role of trophallaxis as honest signal and inhibitory means in regulating reproductive development in C. secundus could be confirmed. Conflict intensity was greatly influenced by wood resource: workers were more likely to stay and fight for inheritance within nests that are resource rich, while when food gets limited dispersal conflict was most pronounced. Thus, individuals did continually assess the ecological (resources) and societal conditions (presence of reproductives, relatedness) and adjusted their developmental decisions in order to maximize own fitness. The developmental potential is linked to the moulting interval, as only individuals in the sensitive phase are able to react to a changing situation like orphaning. Thus the sensitive phase, besides honest signalling (via cuticular hydrocarbon profiles and trophallaxis) might be an further mechanism potentially regulating conflict in C. secundus, as it restricts the number of individuals capable of becoming neotenic in a ‘fair lottery’ process.

Monospecific stands of invasive plant species are found in nearly all known ecosystems and can cause permanent lasting ecosystem damage via deleterious effects in soils. These deleterious soil effects are a proposed mechanism which drives invasions by plants and are known to be influenced by kin recognition in plants. Uncovering whether invasive species utilize kin recognition to facilitate their own ecological persistence via soil conditioning will allow us to better understand the drivers of plant invasions and help combat them. In my master’s thesis, I examined the role of kin recognition and kin selection on soil effects. I grew groups of Potentilla recta in groups of maternal half-sibs or strangers to condition the soil. I then grew a second generation of plants in that conditioned soil to determine the impacts of soil conditioning effects on plant performance. I found soil conditioning by groups of plants affected the performance of a second generation of plants based on the relatedness of the conditioning plants. Further, these soil effects of conditioning selectively benefit future individuals of a subsequent generation based on their relatedness. Moreover, these soil effects only existed in soil that has not been sterilized, indicating these soil effects depended on soil microbes. / Thesis / Master of Biological Science (MBioSci) / Invasive plants form dense stands of same-species individuals that can cause lasting deleterious effects to the soil. These deleterious soil effects have been proposed as a mechanism driving plant invasions. In my master’s thesis, I examined the role of kin recognition and kin selection on soil effects. I first grew groups of Potentilla recta in groups of maternal half-sibs or strangers to condition the soil, and then grew a second generation of plants in that conditioned soil to determine the impacts on plant performance. I found that soil influenced by groups of related plants affect increased the performance of a second generation of plants, particularly if the second generation was related to the first. Moreover, these soil effects only existed in soil that has not been sterilized, indicating these soil effects depended on soil microbes. I found that these soil effects of conditioning selectively benefited future individuals of a subsequent generation based on their relatedness.

<p><strong>ABSTRACT</strong></p> <p>As plants are sessile organisms, detecting the presence of neighboring plants and exhibiting competitive behavior to acquire limiting resources is crucial. One of the ways plants respond to belowground competition is by allocation to fine roots in order to acquire the limited resources. However, this phenotypic plasticity can be costly as it assigns resources away from reproduction. Being able to recognize the relatedness of one′s neighbours and preferentially compete with strangers is a beneficial trait that can minimize the costs of competition with relatives and increases inclusive fitness. Many studies have looked at the association between resource availability and competition in plants while others have observed kin recognition in several plants species. However, no one has yet studied the effect of resource availability on kin recognition in plants. Here, I looked at root architecture to test if there is an association between kin recognition and nutrient availability in <em>Cakile edentula</em>.</p> <p>I found that the root system architecture is highly plastic and complex, showing variable responses to neighbour identity signals and resource availability. The results from the four experiments demonstrate that the responses of <em>C. edentula </em>to neighbour relatedness are dependent on nutrient availability. Additionally, this study also indicates that kin recognition in <em>C. edentula</em> does not require root contact; instead it occurs through a signal found in soluble compounds excreted from plants, possibly root exudates, as observed in <em>Arabidopsis thaliana</em> <em>(</em>Biedrzycki et al. 2010).</p> <p>In conclusion, this study provides novel findings regarding the dynamics of root behavior in response to nutrient availability and the relatedness of neighbours.</p> / Master of Science (MSc)

Group living is a widespread social system among animals. Within these groups, decisions on interactions between individuals can be facilitated through knowledge about individual identity and kinship. Individual identity allows for the recognition of individuals from past interactions and thus, information on likelihood of reciprocity and group-membership can be gained. The benefit for cooperative interactions, specifically, increases with the level of relatedness between the helper and the recipient. Thus, knowing who is kin, is an essential ability among group-living species and remembering individual identity helps to maintain long-term relationships and inform future decisions. Kin recognition can be facilitated through temporal and spatial overlap (i.e. familiarity) or through phenotypic-templates (i.e. phenotype matching). The goal of this thesis was to explore recognition in the joint-nesting pūkeko (Porphyrio melanotus melanotus). For the first portion of this thesis (Chapter II), I tested for evidence of phenotype matching in pūkeko using a cross-fostering experiment. Comparing survival and growth between fostered and non-fostered offspring, I provide evidence that pūkeko do not use phenotype matching as their mechanism for kin recognition. In Chapter III, I show that pūkeko chick distress calls may have an individual and group signature. I found variation in the vocal parameters between individual chicks and social groups. I also tested for response of adults towards chick distress calls of their own group. Using a playback-choice experiment, I report a biased response of adult pūkeko towards the distress call of their own group's chicks rather than the call of a distressed chick from a foreign chick. / Thesis / Master of Science (MSc) / Kin recognition is an essential ability for social species. Knowing whom is kin can help inform decisions on cooperation and conflict. I explored whether the joint-nesting pūkeko use familiarity or phenotype matching to recognise cross-fostered offspring. I experimented to determine if adult pūkeko can recognise the distress vocalizations of chicks in their group. I found no evidence that pūkeko use phenotypic templates to recognise cross-fostered chicks as non-kin. However, adult pūkeko showed a bias in response towards the distress calls of their own versus unfamiliar chicks. Individual chick distress calls, while variable from day-to-day, show group-specific similarities.